In recent years, there have been great advancements in the speed, power, and complexity of integrated circuits. Some types of integrated circuits comprise thin film resistors. When integrated circuit devices that contain thin film resistors are manufactured, different methods may be employed for manufacturing the thin film resistors.
In some prior art methods for manufacturing a thin film resistor the thin film resistor is located at the same level as a conductor interconnect layer. A major disadvantage of this design is that a resistor protect layer (e.g., titanium tungsten (TiW)) that covers the thin film resistor has a topography from which the conductor interconnect layer must be etched away. The resistor protect layer etches in the same dry etch chemistry as the interconnect conductor. This presents a dilemma in that in order to reduce the step height, a thinner resistor protect metal layer is needed. But a layer that is thin enough that will not leave conductive stringers is too thin to survive the conductor dry etch process.
In U.S. Pat. No. 6,645,821 a method is disclosed for manufacturing a buried thin film resistor having end caps defined by a resist mask. A major disadvantage of this design is that a resist mask is incompatible with many of the etchants that are used to remove the resistor protect layer. For example, the thin film resistor in U.S. Pat. No. 6,645,821 states that a resistor protect layer of titanium tungsten can be etched with hydrogen peroxide in a resist pattern. This is a problem because the resist material etches in hydrogen peroxide. This makes the resist material unsuitable as a masking material.
Therefore, there is a need in the art for an efficient system and method for efficiently providing a resistor protect layer that is able to protect a thin film resistor during the steps of a manufacturing process.